gup: convert FOLL_TOUCH case in follow_page_pte() to folio

We already have the folio here, so just use it, removing three hidden
calls to compound_head().

Link: https://lkml.kernel.org/r/20241002151403.1345296-1-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>